I built an Arduino board from scratch and I am dying to test it out, but I have nothing to hook it up to my computer with. I have a spare Serial port on the back of my computer, but since Serial uses 10V, I need to build a very simple circuit that converts the 5V from the Arduino to the 10V for the RS-232/Serial port on my computer. I need 4 1uF caps. I am going to be using ceramic...but something that I never looked at whenever I built an electronic, was the tolerance rating. Odd, yes, but its true. Better now than never I suppose...So, in general, is it better for a capacitor to have a tolerance of +/- 1% or +/- 5% or +/- 20%. What does tolerance really mean to me and to the application? Thanks.